1. Field of the Invention
The present invention generally relates to a vaccine composition and, more particularly to a vaccine composition against Streptococcus pyogenes infection and comprising amino acid sequence of streptococcal pyrogenic exotoxin B.
2. Description of the Related Art
Streptococcus pyogenes is one of major causes of human disease and suffering worldwide, generally leading to invasive infection on organisms. S. pyogenes has several virulence factors that enable it to attach to hosts and to evade the immune response thereof. Wherein, streptococcal pyrogenic exotoxin B (SPE B) is one of major virulence factors, and which can degrade properdin and complements, especially for complement C3 in hosts, blocking downstream response of complement system, such as anti-microbial function of neutrophils, so as to result in serious invasion of S. pyogenes, tissue damages, even death.
The SPE B is a conserved gene of S. pyogenes, with almost all strains of S. pyogenes comprising speB gene, and with 89 speB alleles being found worldwide. The SPE B has 398 amino acids, being around 42 KDa, including a prosegment (about 14 KDa) at N-terminal thereof, and a protease (mSPE B) being 28 KDa.
A conventional vaccine against Streptococcus pyogenes infection, comprising an inactivated SPE B (being an immunogenic virulence protein) that is prepared by mutating the 192nd amino acid (cysteine) of SPE B to serine via site direct mutagenesis, is currently developed, with the conventional vaccine activating response of complement and downstream mechanism thereof to achieve anti-microbes effects in hosts. However, 70% hosts suffer from autoimmune responses, rheumatic heart disease and nephritis for example, after inoculation of the said conventional vaccine, and therefore, it is insufficient in practice use and poor to be further applied on clinical medicine.
Hence there is a need of providing a new vaccine, for improving the said disadvantages.